In order to further process any packaged yarn it is necessary to withdraw such yarn from the package onto which it has been wound at the conclusion of a previous process. It is essential for satisfactory subsequent processing that the yarn can be withdrawn from the package in an even manner, without undue tension fluctuations or yarn breakages. In consequence it is important that the package be wound in such a manner that the offtake performance of the package meets with certain requirements. It follows therefore that it is desirable to know the offtake performance of a package wound under certain winding conditions, so that such winding conditions may be adjusted if necessary to ensure that packages wound under determinable conditions have the requisite offtake performance.